the same syntax and be case insensitive. Also relocated the character type macros
into lib/elixir/include/elixir.hrl so that they didn't need to be defined in both
lib/elixir/src/elixir_interpolation.erl and lib/elixir/src/elixir_tokenizer.erl.
Added to the erlang and elixir unit tests to test the new syntax.
The following code:
counter = 1
counter = 2
Is now rewritten internally to:
counter = 1
counter@1 = 2
Which gives us a couple things:
1. Better debugging
2. We can now show warnings for rebound variables not used
Elixir also keeps `_@` prefix to store internal variables
(for example, `_@1`, `_@MODULE`, etc).
Closes#607.